jim, it's, it's a changing situation. but certainly it is a dramatic scene. it almost looks like a war zone, streets empty, we don't know how many officers are on the scene. but the tension seems to be remarkably high. there's some thought that perhaps dzhokah tsarnaev is holed up and is being negotiated with at this point. >> alex, that's exactly right. you know when you're in command of a situation like this, i always like to break it down to the main things that handle the main crisis points and address those. and there's three interlocking rings here that are affecting boston and the citizens. and that's what the commanders have got to focus on. one is the standoff with dzhokhar, we can talk about how that interlocks and what's going on there. the second is, the placement of another pressure cooker device in the city that they've located. and the question of are there more. and then the third interlocking circle is, whether or not there's these two accomplices, as pete williams described and maybe a person on an amtrak train who was an accomplice. these a